Size for glass fibers

ABSTRACT

A size for glass fibers is disclosed, the size comprising an oxidized polyolefin, a polymeric film former and an organic acid, preferably terephthalic acid or isophthalic acid.

This is a division of application Ser. No. 455,789, filed Jan. 6, 1983,now U.S. Pat. No. 4,448,917.

TECHNICAL FIELD

This invention relates to a size for glass fibers.

In one of its more specific aspects, this invention relates to a sizefor glass fibers employed in reinforcing polypropylene.

One very satisfactory size is a glass fiber coating comprising anoxidized polyolefin, a silane coupling agent and, as a film former, acarboxylated high molecular weight elastomer having a molecular weightof at least about 200,000. The composition has been found to provide anexcellent bond between the glass fibers and the polyolefin matrix intowhich such coated glass fibers have been incorporated for reinforcingpurposes.

There now has been developed an improvement in the above-described size.This improvement results in an increase in tensile strength, flexuralstrength, heat distortion resistance and impact strength of theinjection molded polypropylene into which glass fibers, coated with theimproved size, are incorporated.

STATEMENT OF THE INVENTION

According to this invention there is provided a glass fiber sizecomprising the residue obtained by removing water from an aqueouscomposition comprising a polyolefin latex, a silane, a polymeric filmformer, preferably one having a molecular weight of at least about200,000, a base and an organic acid selected from the group consist ofsubstituted benzoic acids, benzenedicarboxylic acids,benzenetricarboxylic acids, benzenetetracarboxylic acids,benzenepentacarboxylic acids, benzenehexacarboxylic acids,cyclohexanedicarboxylic acids, fatty acids, alphatic diacids, aliphaticpolyacids, cinnamic acids, benzenediacrylic acids, benzenediaceticacids, naphthoic acids, naphthalenedicarboxylic acids,naphthalenedisulfonic acids and anhydrides of the aforesaid acids.

Also according to this invention, there is provided glass fibers sizedwith the aforesaid size and polyolefin resins incorporating glass fiberssized with the aforesaid size.

DESCRIPTION OF THE INVENTION

The method of this invention is employable with any size and type ofglass fiber. It is also employable with any type of polyolefin resinincluding polypropylene, polyethylene, and the like.

This invention can employ any suitable method of applying the size tothe glass fiber and any suitable method of incorporating the sized glassfiber in the polyolefin.

In the preferred embodiment of the invention, the size composition willbe comprised of the following:

    ______________________________________                                                          % By Weight                                                                              Pounds Per                                       Component         As Received                                                                              100 Gals.                                        ______________________________________                                        Terephthalic Acid 2.2        18.8                                             Ammonium Hydroxide                                                                              2.2        18.8                                             Oxidized Polypropylene Latex                                                                    7.5        62.6                                             Carboxylated SBR Latex                                                                          2.8        23.4                                             g-amino-propyltri-                                                                              1.0        8.4                                              ethoxysilane                                                                  Deionized water   Bal.       Bal.                                             Total             100.00     834.00                                           ______________________________________                                    

The size can comprise any emulsified acid grafted or oxidizedpolypropylene latex. The polypropylene latex will be included in thesize composition in an amount within the range of from about 0.5 toabout 25 weight percent.

One suitable oxidized polypropylene latex is Epolene E-43 made byEastman Chemical. This material is emulsified by Proctor Chemical,Salisbury, N.C., and the emulsion is called "Icopol OC."

Any suitable carboxylated high molecular weight latex having asolubility parameter similar to that of the oxidized polyolefin latexcan be employed. This material will be included in the size compositionin an amount within the range of from about 0.5 to about 15 weightpercent.

One suitable material is available from the Goodyear Tire and RubberCompany, Akron, Ohio as LPR-6599. This material comprises a carboxylatedstyrene-butadiene latex having an approximate styrene/butadiene ratio of65/35, a synthetic anionic emulsifier, a total solids content of 53, aBrookfield Viscosity of 150 cps., a pH of 8.5, a surface tension of 50dynes/cm., a specific gravity of 1.022 and contains 8.5 pounds of latexper gallon. This material acts as a strand integrity agent and, while amaterial comparable to the above is preferred, other materials such aspolyurethanes, epoxies, polyesters, poly (vinyl acetates) acrylics, andcombinations thereof can be employed.

Any suitable amino silane can be employed. Suitable silanes includegamma-amino-propyltriethoxysilane, N-(beta-aminoethyl)-gammaaminopropyltrimethoxysilane and polyaminofunctional silanes. Suitablematerials include A1100, A1120 and A1130, respectively, all of which areavailable from Union Carbide Corporation, New York, N.Y. This materialwill be included in the size composition in an amount within the rangeof from about 0.1 weight percent to about 5 weight percent.

In the preferred embodiment of this invention, the acid is eitherterephthalic acid or isophthalic acid, either of which will beincorporated in the size in an amount within the range from about 0.5 toabout 4 weight percent. In the most preferred embodiment of theinvention, the acid will be terephthalic acid which will be incorporatedin the size in an amount of about 2.2 weight percent.

In the preferred embodiment of the invention, a first premix is preparedby mixing 8.3 pounds of the silane into 40 gallons of the water andslowly adding 18.8 pounds of the terephthalic acid. 18.8 pounds ofammonium hydroxide are then introduced into the resulting composite.

A second premix is prepared by adding 62.6 pounds of Icopol OC to 10gallons of water. This composite is added to the first premix to formcomposite I.

A third premix is prepared by adding 23.4 pounds of SBR latex to 10gallons of water. This mixture is added to composite I to form compositeII.

Composite II, the final size composition, is then agitated while beingmaintained between 50° and 70° F. It should have a pH within the rangeof 8-9, and a viscosity at 60° F. in the range of 10 to 20 cps.

The glass size of this invention can be applied to glass fibers usingconventional methods. It will preferably be applied to the glass fiberin an amount to impart to the fiber a loss on ignition within the rangeof from about 0.2 to about 3.0 weight percent and preferably from about0.7 to about 0.8 weight percent.

The sized glass strand will be dried and collected in the usual manner.

The following data demonstrate the improved mechanical and thermalproperties of polypropylene reinforced with 20 weight percent ofidentical glass fibers sized to the same extent with three differentglass sizes.

Size I is a size of the type described herein except that instead ofterephthalic acid, bis-maleamic acid was employed at a weight percentageof 3.25, as suggested in U.S. Pat. No. 4,278,586 issued July 14, 1981.

Size II is a size of the type described in U.S. Pat. No. 3,936,415 whichis basically a comparable size but without the presence of the acid.

Size III is comparable to that of U.S. Pat. No. 3,936,415 into whichterephthalic acid has been incorporated as described above, and which isthe size of this invention.

Tests were made under comparable conditions in which thepolypropylene-glass composite was extruded and the extrudate wasinjected molded.

Results were as follows:

    ______________________________________                                        Polypropylene-Glass                                                           Plus Size No.   I          II      III                                        ______________________________________                                        Tensile Strength, (MPa)                                                                       60         45      59                                         Tensile Modulus, (GPa)                                                                        5.3        5.4     5.6                                        Elongation, (%) 2.43       1.8     2.2                                        Flexural Strength, (MPa)                                                                      99         76      99                                         Flexural Modulus, (GPa)                                                                       4.6        4.7     4.7                                        Izod Impact Energy, (J/M)                                                     Unnotched       278        246     326                                        Notched         100        91      96                                         Heat Deflection Temp,                                                                         137        136     142                                        (°C.) (264 psi)                                                        ______________________________________                                    

It is evident from the foregoing that the size composition of thisinvention imparts to the glass-reinforced polypropylene decidedlyimproved results in all properties tested.

It will be evident from the foregoing that various modifications can bemade to this invention. Such, however, are considered within the scopeof this invention.

We claim:
 1. A glass fiber sized with a size comprising a polyolefinlatex, an amino silane, a polymeric film former and an organic acidselected from the group consisting of substituted benzoic acids,benzenedicarboxylic acids, benzenetricarboxylic acids,benzenetetracarboxylic acids, benzenepentacarboxylic acids,benzenehexacarboxylic acids, cyclohexanedicarboxylic acid, fatty acids,aliphatic diacids, aliphatic polyacids, cinnamic acids, benzenediacrylicacids, benzenediacetic acids, naphthoic acids, naphthalenedicarboxylicacids, naphthalenedisulfonic acids and anhydrides of the aforesaid acidssaid acid or acids being added in an amount sufficient to improve theimpact strength of injected molded polypropylene into which glassfibers, coated with said size, are incorporated.
 2. A glass fiber sizedwith the size of claim
 1. 3. A composite comprising a polymer reinforcedwith glass sized with the size of claim 1.